Texture.java

package de.syscy.hengine.rendering.resources;

//Some imports...

public class Texture extends Resource {
    //ID's of the default textures which are used if the texture hasn't been loaded and the bind method is called
    private static int defaultDiffuseTextureID = -1;
    private static int defaultNormalTextureID = -1;
    private static int defaultDispTextureID = -1;

    //The @Getter and @Setter is from Lombok and this just generates a Getter and a Setter for the variable
    private static @Getter @Setter boolean useMipMaps = true;

    private int id = -1;

    protected Texture(String fileName) {
        super(fileName);

        if (defaultDiffuseTextureID == -1 || defaultNormalTextureID == -1 || defaultDispTextureID == -1) {
            defaultDiffuseTextureID = loadTexture("default/diffuse.jpg");
            defaultNormalTextureID = loadTexture("default/normal.jpg");
            defaultDispTextureID = loadTexture("default/displacement.jpg");
        }
    }

    //Gets automatically called by the ResourceManager is the texture is currently used but not loaded
    @Override
    public void load() {
        super.load();

        this.id = loadTexture(getFileName());
    }

    //Gets automatically called by the ResourceManager if it isn't used for 10secs
    @Override
    public void unload() {
        super.unload();

        //glDeleteBuffers(id); should be the same. I just tried glDeleteTextures to see if this is the origin of the bug
        glDeleteTextures(id);
    }

    public void bind() {
        bind(0);
    }

    //Binds the texture and updates lastUsedTime
    public void bind(int samplerSlot) {
        assert (samplerSlot >= 0 && samplerSlot <= 31);

        updateLastUsedTime();

        glActiveTexture(GL_TEXTURE0 + samplerSlot);
        glBindTexture(GL_TEXTURE_2D, getID());
    }

    //Returns the id if the id isn't -1
    public int getID() {
        if (id == -1 || !isLoaded()) return getDefaultTexture(getFileName());
        return id;
    }

    private static int getDefaultTexture(String fileName) {
        if(fileName.toLowerCase().contains("normal")) {
            return defaultNormalTextureID;
        } else if(fileName.toLowerCase().contains("disp")) {
            return defaultDispTextureID;
        } else {
            return defaultDiffuseTextureID;
        }
    }

    //Loads the texture :D
    private static int loadTexture(String fileName) {
        try {
            BufferedImage image = ImageIO.read(new File("./data/textures/" + fileName));

            int[] pixels = image.getRGB(0, 0, image.getWidth(), image.getHeight(), null, 0, image.getWidth());

            ByteBuffer buffer = Util.createByteBuffer(image.getHeight() * image.getWidth() * 4);

            boolean hasAlpha = image.getColorModel().hasAlpha();

            for (int y = 0; y < image.getHeight(); y++) {
                for (int x = 0; x < image.getWidth(); x++) {
                    int pixel = pixels[y * image.getWidth() + x];
                    buffer.put((byte) ((pixel >> 16) & 0xFF));
                    buffer.put((byte) ((pixel >> 8) & 0xFF));
                    buffer.put((byte) ((pixel) & 0xFF));
                    if (hasAlpha) buffer.put((byte) ((pixel >> 24) & 0xFF));
                    else
                        buffer.put((byte) (0xFF));
                }
            }

            buffer.flip();

            int id = glGenTextures();

            glBindTexture(GL_TEXTURE_2D, id);

            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

            glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
            glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);



            if(useMipMaps && Util.openGLVersion >= 30) {
                glTexParameterf(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);

                glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
                glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR);
            } else {
                glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
            }

            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, image.getWidth(), image.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);

            return id;
        } catch (Exception ex) {
            if(getDefaultTexture(fileName) != -1)
                return getDefaultTexture(fileName);
            else
                return -1;
        }
    }
}